Archived "Brake" light and ABS light on!!

[DCMille290]

I replaced the front brake pads a couple of days ago, as I have for the last 4 years, without incident. Now today both the "ABS" and dash red "Brake" light are on. (It's not the emergency brake switch stuck on. )

Everything seems to be OK, no leaks or low level brake fluid. Brakes seem to work OK, but I go back on the road in a week and need to figure out what's up.

Feedback appreciated.



David "DC" Miller

Marbleman

 

[Bob V]

Sounds like a vacuum problem, do the AC and Heater vents work? If not, or they are slow, check for a disconnected hose or bad pump.

Bob

 

[RJ2]

Did you hook up to any stange trailer connections? RJ

 

[DCMille290]

Bob... . Seems fine with A/C and vents, no hoses off that I can see.



RJ2... ... You know I had to replace my RV cord on the 5th wheel and I don't know if I connected my breakaway wires to the correct wires on the trailer cord or not. I asked at a RV service center... ... . then did the brakes on the truck last week before leaving WI for AR... ..... what are you thinking?? Tripped a code? Or maybe wiring for breakaway switch is incorrect.



David

 

[Paul Herioux]

If the trailer wiring was messed up it may have blown the brake lamp fuse which will disable the ABS system. Check to see if you have brake lights and go from there.

 

[BCFAST]

Sorry guys, but I think you're barking up the wrong tree on this one... . your problem is most likely that pesky little ABS sensor in the rear diff. About $37 at the stealer, and a simple R&R.

Brian

 

[DCMille290]

Hey BCFast..... Seems you may be heading in the right direction, been having nothing but troubles with my Dana, I am on my third rearend now.

What's involved with R&R of the ABS sensor??



David

Marbleman

 

[BCFAST]

What's involved? About $37, a wrench, and about 10 minutes of your time! Really, it's a stupid little job and the sensor is a known "wear-out" item... but I'm quite sure this'll cure what ails ya!

 

[lschultz]

Take that sensor out and wipe it with one of those Magic Cloths Just kidding. I would say that what it is too. Its nothing to take one out. But when my sons went out on his 99 I said I(old man)will change it for you. Took the bolt loose went to pull it out-stuck so I pull harder and break the da** thing off. But the broken off piece wasn't hard to get out.

 

[DCMille290]

Wipe it off with a Magic Cloth... . hhmmmmm... . why didn't I think of that?

Thanks for the diection guys... ... I'll go out and pull it off today and let you all know what I find.



David "DC" Miller

Marbleman

 

[mopars1]

David, you may want to save some time since you stated the wiring to the trailer might not be correct. A blown brake system fuse will turn on the red and amber brake lamps on the dash. I would check that first if you haven't yet. It is a lot cheaper than buying a sensor for the rear axle without knowing for sure. Just my quarter's worth.



David

 

[DCMille290]

Mopars... ... I checked the fuses inside the truck on the left side, and under the hood on left side and cannot find any fuses blown. I am assuming that the breakaway switch is wired correctly because the lights didn't come as soon as I hooked up the trailer cord, it was a couple of days on the road later.

But I will for sure double check them again.



David

 

[DCMille290]

OK... . I went out and crawled under the truck and located a small plug with a 2 connector wire harness going to it, figured out how to get the plug and clip off, but I don't see how the assembly comes off the top of the rearend housing. There is what appears to a square metal bracket around the actual sensor connection but I cannot see what holds it to the housing... ... ... suggestions??



David

 

[Bill Lins]

No disrespect intended to those who are trying to help, but I have a question. Didn't the problem occur AFTER you replaced the front pads? How would that affect the rear axle sensor?



When you retracted the pistons in the calipers, did you open the bleeders first? If not, you applied pressure to the ABS system in the reverse of normal direction. That tends to scramble the ABS's little electronic brain and could make the warning lights come on. You may have to take the truck in to have the ABS "re-centered". Good luck.

 

[DCMille290]

Originally posted by Bill Lins

No disrespect intended to those who are trying to help, but I have a question. Didn't the problem occur AFTER you replaced the front pads?



How would that affect the rear axle sensor?

When you retracted the pistons in the calipers, did you open the bleeders first? If not, you applied pressure to the ABS system in the reverse of normal direction. That tends to scramble the ABS's little electronic brain and could make the warning lights come on. You may have to take the truck in to have the ABS "re-centered". Good luck.

Yes, the problem started a day or so after the brake job, front pads.



Bill... ..... No, I did not open the small bleeders, and have not since I been doing the front brakes on this truck. That's 4 years at 2-3 sets up front a year.

All I do is open the top of the master cylinder an keep on eye on the fluid level so it doesn't overflow.



I wonder is disconnecting the batteries for at least 1 hour will reset whatever computer code that was tripped??



BTW... ... the sensor mounted on top of the rearend on this truck is a magnet and I remember for the last overhaul that there is a ring in the rearend for the speedometer that was left out and had to be R&R in order for the speedo to work. That's the only thing I could find wired to the readend, anywhere.

Checked all fuses again, nothing.



David

Marbleman

 

[wtrenholm]

DCMille290,



If I remember right, in 98 they started using the rear axle speed sensor for RWAL and the speedo inputs. So, if the speedo works it's I doubt the rear sensor is faulty (assuming you don't have 4 wheel ABS). Are the lights on steady or do they come on and go out then come back on when driving?



You have to have a scan tool to access trouble codes. Also, disconnecting the battery will clear the stored codes but if the problem still exists it will just turn back on during the next drive cycle.



A half hour of diagnostic time at a shop is cheaper than a unneeded part. Another idea is a tech school, we typically don't charge for diagnostic time where I teach and have factory scan tools for various manufacturers.



HTH

Wayne

 

[Maximus]

If the problem is the rear ABS sensor, when you start driving your speedo will read 0 mph until you hit 15-20 mph. It will then jump to the correct speed.

 

[Bill Lins]

Originally posted by DCMille290





Bill... ..... No, I did not open the small bleeders, and have not since I been doing the front brakes on this truck. That's 4 years at 2-3 sets up front a year.



I wonder is disconnecting the batteries for at least 1 hour will reset whatever computer code that was tripped??



David

Marbleman

Mebbe your luck finally ran out re the bleeders. It is my understanding that the problem occurs within the ABS unit itself, but disconnecting the batteries might be worth a try. How long has it been since the axle was overhauled? Could the tone ring have come loose and either contacted the sensor or moved too far from it?

 

[DCMille290]

Originally posted by Bill Lins





Mebbe your luck finally ran out re the bleeders. It is my understanding that the problem occurs within the ABS unit itself, but disconnecting the batteries might be worth a try. How long has it been since the axle was overhauled? Could the tone ring have come loose and either contacted the sensor or moved too far from it?

If the problem lies within the ABS unit, what's the cure???



I am scheduled to have the cover pulled from the diff in the AM. This is a brand new, 15,000 miles on it, rearend Dodge installed in March. Although since it is over the 12K warranty they are no help. So, I found a drivetrain shop here in AR and we'll see what happens. Maybe I can solve both problems at the same time.



Thanks everyone for your help. I'll let you all know what happens.



David

Marbleman

 

[Bill Lins]

Originally posted by DCMille290





If the problem lies within the ABS unit, what's the cure???

David

Marbleman

I understand the dealer has to "re-center" the ABS unit- dunno what that means. Hey, did you ever get my check?